How can i add a second drive to nginx server?

I have a server having two drives each of 2TB. First drive is mounted to "root" (which is called "/") and the second drive is mounted to /mnt/disk1. I am serving my files from first hard drive at location /usr/share/nginx/html/downloads/ with this default configuration below:

With this approach you will have following situation:
If you access via http://ip_address/downloads, you will see only content from first disk /
If you access via http://ip_address/downloads2, you will see only content from second disk /mtn/disk1.

If you can use multiple locations, e.g. downloads and downloads2, this will get your job done. Problem is if you want to serve files from both disk on one location - /. You will have hard time with this.